Front End Geometry In The...
Front End Geometry In The Middle Of A Corner Completely Compressed At Full Travel Here is the difference when the car is traveling through the corner. Notice the shocks are working to keep the car as low as it can be. But look at the camber we have lost in both tires. The right front has gained negative camber and the left front has lost positive camber. Knowledgeable crew chiefs will expect this and set their cars up for this loss.
When making that big of a jump in the right-rear spring, it could cause your car to be very loose all the way around the corner. Take it easy the first couple of laps after changing the spring and learn how your car is going to react. A typical Late Model spring setup will look like this: (This is on a Late Model that runs the standard coil-over shock/spring setup.)
|Late Model Spring Setup |
|LF 250 ||RF 250 |
|Front sway bar: 1.5 |
|LR 200 ||RR 400 |
Shocks are vitally important as well when it comes to making the BBSS setup work. Shocks can be summed up in two different cycles: Compression, which is when the shock is compressed, and rebound, which is when the shock starts to extend back to its normal length. The first thing to realize is the need for significantly more rebound in the front shocks to help pin the nose to the track. This means that it is harder for the shocks to extend back to their normal length. This is especially relevant to the left front, as it requires more rebound than the right front. I had so much rebound in my left-front at Iowa Speedway last fall that once the shock was compressed I could not-no matter how hard I pulled-extend the shock.
The rebound, coupled with the large right-rear spring and the large sway bar, all work to pin the front tires to the track. That way the nose is as low as it can be, giving that aero advantage, and the front tires are being forced to give you maximum traction. Run a little lighter on the compression because you want to make it easier for the nose to dive entering the corner.
This car is sitting in the...
This car is sitting in the shop and the camber with no travel is 9.1.
One thing to remember is that the BBSS is most successful on a track that has less banking, particularly between 0-10 degrees. When a car travels in the corner of a banked turn, the banking pushes the nose to the asphalt naturally because of the faster speeds. That's not to say that the same concepts and setups won't work on tracks with more banking. It's just that the results you are trying to achieve on flat tracks are created naturally by the banking on banked tracks. You will need stiffer springs in the front of the car at the tracks with more banking. That's to keep the front end from dragging in the corners.
When you choose to run the BBSS, remember that you want to run the softest front springs possible without bottoming out in the corners. Also make sure you are not coil-binding the front springs. If you are coil-binding either of the front springs, you are adding huge amounts of stress to the tire. When the spring is coil-bound, the tire now acts as the spring, and laps run like this will eventually damage the carcass of the tire and put you out of the race.
The car is now at three inches...
The car is now at three inches of travel and notice that we have lost 1 degree of camber.
Another thing teams often overlook is camber. With the softer springs in the front, the front end is going to travel more than normal. When it travels, the front tires are going to be pushed up into the wheel wells, but they are not going to travel straight up. Instead, they are going to travel in at an angle. Any negative camber you have in the right front is going to gain negative camber, and expect a half to a full degree of camber loss. Loss means you will gain negative, so if you are at -3.5, expect at full travel you will be at -4.5. You will lose camber at the left front as well, so if you are at +6 you can expect to be at +5 at full travel. Knowledgeable crew chiefs will expect this to happen and might run a little less right-front camber and a little more left-front camber to help with the reduction in camber that the car experiences.
I can't over-emphasize how important it is to make sure you test, test, test! When your local track has an open practice day, go there and change things. That is the only way you will find speed. It might mean that you have to be slower on that practice day, but remember the BBSS setup works and has been proven time and time again.
When you test, take plenty of notes, and when you change different springs, shocks, and other variables, make sure you change one thing at a time. That way you can directly see if that spring helped. Once you get a good handle on the BBSS setup it will greatly improve your consistency from track to track.